Fluid seal

Abstract

An annular fluid seal made of an elastomeric material has a body with a radially outer surface and a radially inner surface. The outer surface is contoured to be insertable into the opening in the end of a cylinder. The inner surface has at one side a radially inwardly extending sealing lip for slidably engaging and sealing a piston rod, and at the other side it has a radially inwardly extending wiping flap for wiping the piston rod. Between the sealing lip and the wiper flap is a radially inwardly extending guide member slidably engaging the rod for guiding the rod through the seal. The guide member is much wider than the sealing lip or wiper flap, to withstand radial forces imposed by the rod which would otherwise tend to distort the seal and cause it to leak.

I claim: 
     
       1. A fluid seal comprising: (a) an annular body of an elastomeric material having a radially outer surface, a radially inner surface, and first and second opposite side faces;   (b) said outer surface being contoured to be insertable into a generally cylindrical opening;   (c) said inner surface having: (i) a radially inwardly extending sealing lip having a sealing face for slidably engaging a generally cylindrical shaft in a fluidly sealing manner, said sealing face being generally coaxial with the fluid seal, and said sealing lip having an end surface generally perpendicular to the sealing face and adjacent the first side face; and   (iii) a radially inwardly extending wiping flap for slidably engaging the shaft, said wiping flap having a wiping face generally coaxial with the fluid seal and having an end surface generally perpendicular to the wiping face and adjacent the second side face, the width of the end surface of the sealing lip being greater than the width of the end surface of the wiping flap;     (d) a radially inwardly extending guide member adjacent said inner surface and axially spaced between the sealing lip and the wiping flap, said guide member having a guide face adapted to slidably engage the shaft for guiding the shaft through the seal, said guide face being substantially wider than said sealing face and said guide member being adapted to resist radial movement of said shaft, thereby to limit distortion of said sealing lip, said sealing lip and said guide member being separated by a first channel therebetween, said wiping flap and guide member being separated by a second channel, and said first and second channels extending radially outwardly of the inner surface of the seal and extending around the circumference of said inner surface;   (e) an annular washer or rigid material generally coaxial with the annular body and embedded in said body; and   (f) a respective groove extending around each of the first and second side faces radially outwardly of the respective end surfaces.   
     
     
       2. A fluid seal as claimed in claim 1 wherein the width of the guide face is greater than the width of the sealing face and the width of the wiping face combined. 
     
     
       3. A fluid seal as claimed in claim 2 wherein said elastomeric material has a hardness of from 30 to 60 on the Shore D scale. 
     
     
       4. A fluid seal as claimed in claim 3 wherein said elastomeric material is a castable plastic. 
     
     
       5. A fluid seal as claimed in claim 3 wherein said elastomeric material is a urethane. 
     
     
       6. The fluid seal as claimed in claim 1 wherein the guide member is of a harder material than said elastomeric material. 
     
     
       7. The fluid seal as claimed in claim 1 wherein the guide member comprises a metal washer. 
     
     
       8. The fluid seal as claimed in claim 1 wherein the guide member comprises a metal washer, said washer being recessed within, and being co-axial with, the annular body. 
     
     
       9. A fluid seal as claimed in claim 1 wherein said guide member is formed as to part of its lateral width by a metal washer and as to part of its width by an elastomeric material. 
     
     
       10. A fluid seal as claimed in claim 9 wherein said washer has a radially inner surface, the radially inner surface of said washer being covered by a thin layer of elastomeric material. 
     
     
       11. A fluid seal as claimed in claim 9 wherein said radially inner surface of said annular body includes a first radially outwardly extending circumferential channel between said sealing lip and said guide face, and a second radially outwardly extending circumferential channel between said wiping flap and said guide face. 
     
     
       12. A fluid seal comprising: (a) an annular body of elastomeric material having a radially outer surface, a radially inner surface and first and second opposite side faces, said outer surface being contoured to be insertable into a generally cylindrical opening;   (b) said inner surface of said body having a radially inwardly extending sealing lip having a sealing face for slidably engaging a generally cylindrical shaft in a fluidly sealing manner;   (c) a radially inwardly extending guide member adjacent said inner surface and axially spaced from said sealing lip and having a guide face adapted to slidably engage the shaft for guiding the shaft through the seal, said guide face being substantially wider than said sealing face and said guide member being adapted to resist radial movement of said shaft, thereby to limit distortion of said sealing lip, said sealing lip and said guide member being separated by a first channel therebetween, said first channel extending radially outwardly of said inner surface and extending around the circumference of said inner surface; and   (d) an annular washer of rigid material generally coaxial with the annular body and embedded in said body adjacent said second side face, at least a portion of the lateral width of said washer being located between the guide face and the outer surface of the seal to stiffen the guide member, the ratio of the lateral width of the washer to the lateral width of the annular body being about 0.15 to 0.65.   
     
     
       13. A fluid seal as claimed in claim 12 wherein said rigid material chosen from the group consisting of metal, nylon and hard plastic which is harder than said elastomeric material of said annular body. 
     
     
       14. A fluid seal comprising: (a) an annular body of elastomeric material having a radially outer surface, a radially inner surface and first and second opposite side faces, said outer surface being contoured to e insertable into a generally cylindrical opening;   (b) said inner surface of said body having a radially inwardly extending sealing lip having a sealing face for slidably engaging a generally cylindrical shaft in a fluidly sealing manner;   (c) a radially inwardly extending guide member adjacent said inner surface and axially spaced from said sealing lip and having a guide face adapted to slidably engage the shaft for guiding the shaft through the seal, said guide face being substantially wider than said sealing face and said guide member being adapted to resist radial moment of said shaft, thereby to limit distortion of said sealing lip, said sealing lip and said guide member being separated by a first channel therebetween, said first channel extending radially outwardly of said inner surface and extending around the circumference of said inner surface; and   (d) an annular washer of rigid material generally coaxial with the annular body and embedded in said body adjacent said second side face, said washer having a radially inner surface spaced about 0.050 to 0.070 inches radially outwardly of said guide face.   
     
     
       15. A fluid seal as claimed in claim 12 wherein said sealing lip is adjacent said first side face, said inner surface further having a radially inwardly extending wiping flap for slidably engaging the shaft, said wiping flap being adjacent said second side face, said guide member being between the sealing lip and the wiping flap. 
     
     
       16. A fluid seal as claimed in claim 15 wherein the guide member and wiping flap are spaced axially apart and define a second channel extending between the guide member and the wiping flap, said second channel extending radially outwardly of the inner surface of the seal and extending about its circumference. 
     
     
       17. A fluid seal as claimed in claim 15 wherein said sealing face is generally coaxial with the fluid seal and said sealing lip has an end surface generally perpendicular to the sealing face and adjacent the first side face. 
     
     
       18. A fluid seal as claimed in claim 17 wherein said wiping flap has a wiping face generally coaxial with the fluid seal and has an end surface generally perpendicular to the wiping face and adjacent the second side face. 
     
     
       19. A fluid seal as claimed in claim 18 wherein a respective groove extends around each of the first and second side faces radially outwardly of the respective end surfaces. 
     
     
       20. A fluid seal as claimed in claim 1 or 14 wherein said rigid material comprises steel. 
     
     
       21. A fluid seal as claimed in claim 1 or 14 wherein the outside diameter of said washer is smaller than the diameter of said outer surface of the seal. 
     
     
       22. A fluid seal as claimed in claim 1 or 14 wherein said second side face of the seal is coplanar with an outside surface of said washer. 
     
     
       23. A fluid seal as claimed in claim 16 wherein the width of the first channel is greater than the width of the second channel. 
     
     
       24. A fluid seal as claimed in claim 16 wherein the first and second channels are generally V-shaped. 
     
     
       25. A fluid seal as claimed in claim 1, 12 or 14 wherein said radially outer surface has a stepped profile to define a larger diameter part adjacent said first side face and a smaller diameter part adjacent said second side face. 
     
     
       26. A fluid seal as claimed in claim 25 wherein said smaller diameter part of said outer surface has a radially inwardly extending groove about its circumference for receiving an O ring. 
     
     
       27. A fluid seal as claimed in claim 12 or 14 wherein said washer extends radially substantially between the radially outer and inner surfaces of the annular body. 
     
     
       28. A fluid seal as claimed in claim 12 or 14 wherein said washer has a radially outer surface, the radially outer surface of said washer being covered by a thin layer of elastomeric material.